The agency responsible for managing the nation’s federal buildings has repeatedly dropped the ball in its dash to enhance security after the Oklahoma City bombing, government documents reveal.

Since the attack on the Alfred P. Murrah building in April 1995, the General Services Administration has spent more than $1 billion trying to better protect 8,300 federal buildings.

But confidential government reports obtained by The Post paint a disturbing behind-the-scenes picture of that effort.

While the GSA boasted in March 1998 that 90 percent of its 7,800 planned security upgrades were completed, government auditors found some security funds had been poured into beautification projects while millions of dollars in vital equipment remained broken, missing, uninstalled or unused – some of it at 26 Federal Plaza in lower Manhattan and at Kennedy Airport in Queens.

And while the GSA was cutting back on its Federal Protective Service police, many contracted guards were being hired with little training and without background checks.

“We’re inviting another disaster,” said U.S. Rep. James Trafficant (D, Ohio), who is sponsoring a bill to reform the GSA’s security program.

According to a March 1999 report by the GSA Inspector General William Barton, millions of dollars in equipment at 97 buildings surveyed was uninstalled, unused or broken, including:

* Two $46,000 bomb-detecting machines, one in New York and one in Puerto Rico, that were kept in basements and possibly never used.

* A $100,000 alarm system installed in September 1996 in a building used by the Federal Aviation Administration at Kennedy Airport – and never used.

* A broken crash gate left unrepaired for up to nine months at an Oklahoma City building while the GSA waited for an insurance payment to fix it.

* 25 X-ray machines and 32 metal detectors worth more than $2 million found in the basement of a Washington federal building – still in their original cartons.

The IG also found almost $1 million in security funds had been misspent, including $40,000 spent in Chicago to install decorative lighting – under a metal “Flamingo” sculpture – ostensibly to improve security-camera images at night. But the cameras “still could not record color images at night.”

Although the GSA’s computers listed 7,000 improvements completed by March 1998, two audits that year by the IG and the General Accounting Office revealed discrepancies in about half the 180 buildings checked.

Reporting errors included three security cameras at 26 Federal Plaza in New York that were listed as installed but were actually only housings with no wires, and $311,000 in radio equipment for 26 Federal Plaza was reported as installed but wasn’t working.

In October 1999, after the GSA had a chance to address the problems, a GAO official told a congressional panel, “GSA is still not in a good position to know how adequate the security of federal buildings is.”

The GSA’s increasing reliance on contract security guards – a force doubled since 1995 to about 7,000 – was the focus of the inspector general’s most recent audit, issued last March.

The problems uncovered included hundreds of guards working without valid clearances or background checks, and guards untrained in the proper use of security equipment, including X-ray machines, handcuffs and pepper spray.

Asked to comment on the reports, a GSA spokeswoman sent The Post a Sept. 28, 2000, statement to Congress by Public Building Service Commissioner Robert Peck in which he said nearly all shortcomings outlined by the auditors had been addressed.